1. Field of the Invention
The field of the volumetric invention relates to a method and apparatus for rearmounted removable frame extension devices that increase the bed length of pickup trucks and similar vehicles. In a more limited sense the field of this invention relates to a low profile, single rail, cantilevered frame extension apparatus of the type which is solely frame mounted and free of any supporting connections to the vehicle body proper.
2. Description of Prior Art
Extension apparatus for increasing the load carrying capacity for beds on pickup trucks is well known. A search of the prior art, however, does not disclose the combination of a frame mounted box receiver hitch, two-piece, T-shaped (when viewed from above) box beam extension apparatus that is solely single paint, frame-supported and adjustable by an upward fixably and cantilevered angled from a central vehicle-mounted frame location which secures single point box receiver hitch to the truck frame.
The art, instead, centers mostly on complex bed-supported extensions or combination frame/bed cable, rope, rod and rail extension schemes. In a general sense, such prior art has focussed on struts and trusses to increase volumetric load capacity without realizing that load support, weight transfer and stabilization are more important issues.
For instance, U.S. Pat. Nos. 2,712,470 to Cardini and 2,852,303 to Hopson are fairly representative of the art illustrating bed-mounted, U-shaped extension racks. Such carriers and/or racks suffer numerous drawbacks associated with their design and their various methods of attachement. Cardini is U-shaped with two horizontal arms extending from the upper flanges of the truck bed and then descending downward from the horizontal at the bight portion of the U for load carrying capacity.
Hopson has a substantially U-shaped bed within-a-bed and relies upon bed-mounted rollers for extension. Neither of these patents disclose a frame mounted box receiver hitch. Both suffer from unduly stressing the vehicle's components per se. Additionally, these references do not appreciate or recognize the importance of a single point, two axis frame mounted cantilever principle which yields a low profile (i.e. short rearward extension), easily removable and/or installed load extension apparatus.
The U.S. Pat. Nos. to Haigler 4,951,991 and Chamberlin et al 4,932,703 are again U-shaped and respectively rely on unduly complex frame and bed mounting rails and/or cables. In Haigler, a cable is centrally located and the extension is a particularly complex two-rail telescoping frame that is housed under the truck when not in use.
Chamberlin et al discloses a pair of bed-mounted cables suspenders connected as load-support for a horizontal beam member that is centrally pivoted by a stabilizing brace or strut which is connected to a bumper location. These cited prior art patents depict the complexity that is fairly representative of the state of the art.
An even more complex load extension apparatus is shown by the derrick approach described in U.S. Pat. No. 5,120,102 to Cumbie. Cumbie is a slightly different version of the Chamberlin et al philosophy of using cables and trusses for extension purposes. It is a high profile apparatus which relies both on attachment to the vehicle bed and a swivel bolt adjacent to the bumper's trailer ball hitch in order to provide a truss suspension approach. This Cumbie-type apparatus is not desirable for a great number of reasons such as the stresses placed upon the sides of the truck bed by the chains and cables and the stress placed upon the bumper of the Cumbie vehicle.
Having briefly reviewed the typical state of the prior art, it can be seen that several obstacles stand in the path of successfully employing a rear-mounted load handling apparatus. In accordance with this invention, the complexity of the telescoping trusses and extension members has been eliminated. Additionally, the cable and complex two-rail strut or cable philosophy has been discarded.
Finally, the method and apparatus of this invention is simple, durable relatively lightweight and easily removed and quickly re-installed length/height adjustment as needed. With today's popularity for pickup trucks being enjoyed by every member of the family, such apparatus must be suitable for use by women, seniors and teenagers.